# US 8,569,689 B2 · Methods for detecting vitamin C by mass spectrometry > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,569,689 B2 - Document ID: US8569689B2 - Status: Granted - Kind: B2 - Application number: 13/725,049 - Filed: 2012-12-21 - Published: 2013-04-18 - Granted: 2013-10-29 - Earliest claimed: 2008-10-06 - Assignees: Quest Diagnostics Investments Incorporated - Applicants: Quest Diagnostics Investments Incorporated - Inventors: Qibo Jiang; Richard E Reitz; Sum Chan - Web page: https://patentgrep.com/patent/US8569689B2 ## CPC - G01N 33/82: involving vitamins {or their receptors} - B01D 15/08: Selective adsorption, e.g. chromatography - B01D 15/122: {Solid phase extraction} - G01N 30/7233: {interfaced to liquid or supercritical fluid chromatograph (interfaces in general for introducing or extracting samples to be analysed with specially adapted mass spectrometer, see H01J49/04)} - G01N 30/84: Preparation of the fraction to be distributed - G01N 30/88: Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 - G01N 33/487: of liquid biological material - H01J 49/0031: {Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence)} - H01J 49/0036: {Step by step routines describing the handling of the data generated during a measurement} - H01J 49/26: Mass spectrometers or separator tubes - G01N 2030/884: {organic compounds} - G01N 2560/00: Chemical aspects of mass spectrometric analysis of biological material - G01N 2800/02: Nutritional disorders - G01N 2800/52: Predicting or monitoring the response to treatment, e.g. for selection of therapy based on assay results in personalised medicine; Prognosis - H01J 49/0027: {Methods for using particle spectrometers} - H01J 49/004: {Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn} - H01J 49/0045: {characterised by the fragmentation or other specific reaction} - H01J 49/165: {Electrospray ionisation} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract Provided are methods for determining the amount of vitamin C in a sample using mass spectrometry. The methods generally involve ionizing vitamin C in a sample and detecting and quantifying the amount of the ion to determine the amount of vitamin C in the sample. ## Claims ### Claim 1 A method for determining the amount of vitamin C in a body fluid sample by tandem mass spectrometry, the method comprising: (a) purifying vitamin C from the body fluid sample by liquid chromatography; (b) generating a precursor ion of vitamin C having a mass/charge ratio of 175.05±0.5; (c) generating one or more fragment ions of the precursor ion selected from the group of fragment ions having a mass/charge ratio of 114.85±0.5, and 86.85±0.5; and (d) detecting the amount of one or more of the ions generated in step (b) or (c) or both using tandem mass spectrometry and relating the determined ions to the amount of vitamin C in the body fluid sample. ### Claim 2 (depends on 1) The method of claim 1, wherein liquid chromatography comprises high performance liquid chromatography (HPLC). ### Claim 3 (depends on 1) The method of claim 1, wherein liquid chromatography comprises high turbulence liquid chromatography (HTLC). ### Claim 4 (depends on 1) The method of claim 1, wherein the step of purifying vitamin C in a body fluid sample includes one or more purification steps prior to liquid chromatography. ### Claim 5 (depends on 4) The method of claim 4, wherein said purification step comprises protein precipitation. ### Claim 6 (depends on 1) The method of claim 1, wherein said body fluid sample is plasma or serum. ### Claim 7 (depends on 1) The method of claim 1, wherein said ionizing comprises ionizing by atmospheric pressure chemical ionization (APCI). ### Claim 8 (depends on 1) The method of claim 1, further comprising adding a stabilizing agent to the test sample prior to purifying the test sample. ### Claim 9 (depends on 8) The method of claim 8, wherein said stabilizing agent is trichloroacetic acid (TCA). ### Claim 10 (depends on 1) The method of claim 1, wherein said method has a lower limit of quantitation within the range of 10.0 mg/dL and 0.1 mg/dL, inclusive. ### Claim 11 (depends on 1) The method of claim 1, wherein the amount of one or more vitamin C ions determined by mass spectrometry is related to the presence or amount of vitamin C in the test sample by comparison to an internal standard. ### Claim 12 (depends on 1) The method of claim 1, wherein the internal standard is 13C6-L-ascorbic acid. ### Claim 13 A method for determining the amount of vitamin C in a body fluid sample by mass spectrometry, said method comprising: (a) contacting a body fluid sample with a stabilizing agent to inhibit vitamin C degradation; (b) purifying vitamin C from the sample by high performance liquid chromatography (HPLC); (c) generating a precursor ion of vitamin C having a mass/charge ratio of 175.05±0.5; (d) generating one or more fragment ions of the precursor ion selected from the group of fragment ions having a mass/charge ratio of 114.85±0.5, and 86.85±0.5; and (e) determining the amount of one or more vitamin C ions by mass spectrometry, wherein the amount of the determined vitamin C ions is used to determine the amount of vitamin C in body fluid sample. ### Claim 14 (depends on 13) The method of claim 13, further comprising subjecting the sample to a purification step prior to HPLC. ### Claim 15 (depends on 14) The method of claim 14, wherein said purification step is high turbulence liquid chromatography (HTLC). ### Claim 16 (depends on 14) The method of claim 14, wherein said purification step is protein precipitation. ### Claim 17 (depends on 13) The method of claim 13, wherein said mass spectrometry is tandem mass spectrometry.